Method of preparing lithium salts

ABSTRACT

The present invention provides an inexpensive process for the preparation of lithium salts of formula LiX having a desired or required level of purity using lithium chloride and lithium sulfate. In the process of the invention, a lithium salt selected from lithium chloride, lithium sulfate, and combinations thereof is reacted with NaX or KX in a aqueous, semiaqueous, or organic solution and the precipitated salts are removed to obtain the LiX solution of desired purity. Preferably, a semiaqueous solution containing water and an organic solvent is used at some point in the reaction. The process of the invention eliminates the use of highly acidic materials and thus reduces the cost of raw materials and the need for specialized equipment.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to commonly owned provisional applicationSer. No. 60/026,717, filed Sep. 26, 1996, and provisional applicationSer. No. 60/026,738, filed Sep. 26, 1996, and claims the benefit of theearlier filing dates of these applications under 35 U.S.C. §119(e).

FIELD OF THE INVENTION

The present invention is directed to a process for preparing lithiumsalts, and specifically, to an inexpensive process for preparing lithiumsalts from low cost lithium chloride and lithium sulfate.

BACKGROUND OF THE INVENTION

Lithium salts have found utility in various applications. For example,lithium nitrate is known for use in ceramics, pyrotechnics, salt baths,heat exchange media, refrigeration systems, rocket propellants andspecialized concrete applications. Another useful lithium salt, lithiumbromide, is known for use in pharmaceuticals, air conditioning systems,low temperature heat exchange media, drying agent, refrigerationsystems, batteries, medicine and as a humectant.

The conventional method of producing many lithium salts is to combineeither lithium carbonate or lithium hydroxide with acids containing thedesired anion for the lithium salt. For example, the conventional methodof producing lithium nitrate is to react lithium carbonate and/orlithium hydroxide with nitric acid. Nevertheless, this process requireshigh purity raw materials and very expensive plant equipment and metalof construction for the handling of the highly alkaline lithium saltsand concentrated nitric acid.

Similarly, the conventional method of producing lithium bromide is toreact hydrobromic acid with lithium hydroxide or lithium carbonate. Thesaturated solution on cooling precipitates lithium bromide monohydrate,which can be dried to the anhydrous salt. Nevertheless, hydrobromic acidis a very irritating colorless gas that fumes strongly in moist air.Furthermore, hydrobromic acid is classified under DOT regulations, ashighly corrosive, and highly irritative to eyes, skin and respiratorypassages. Therefore, the production of lithium bromide using hydrobromicacid can be quite dangerous.

As described above, the use of highly acidic materials in the formationof lithium salts is undesirable as the materials are generally hazardousand require special equipment. Furthermore, the above processesgenerally do not produce high yields of the lithium salts being producedand therefore cannot be used where high purity lithium salts aredesired. Therefore, there is a need to provide an inexpensive method ofincreasing the purity of the lithium salts without using highly acidicmaterials.

SUMMARY OF THE INVENTION

The present invention provides an inexpensive process for thepreparation of lithium salts using lithium chloride and lithium sulfate.The process of the invention eliminates the use of highly acidicmaterials and thus reduces the cost of raw materials and the need forspecialized equipment. The process produces lithium salts of desiredpurity without compromising safety in the production of these salts.

The process of the invention comprises preparing a lithium salt offormula LiX of desired or required purity by reacting a lithium saltselected from lithium chloride, lithium sulfate, and combinationsthereof with NaX or KX in an aqueous, semiaqueous and/or organicsolution and removing the precipitated solids from the semiaqueoussolution to obtain a LiX solution of desired purity. Any combinations ofsolvents can be used in the invention but preferably the lithium saltand NaX or KX salt are reacted in a semiaqueous solution containingwater and an organic solvent. Nevertheless, the semiaqueous reactingstep can be preceded by an aqueous reacting step or can be replaced bysuccessive aqueous and organic reacting steps. Typically, the organicsolvent in the semiaqueous and organic solutions is selected fromaliphatic ketones, aliphatic alcohols, and mixtures thereof. The processof the invention has been found especially useful for producing lithiumsalts of formula LiX wherein the solubility of LiX in the solution usedis greater than the solubility of the sodium or potassium salts producedas by-products in the reacting step.

Use of sulfate salts as part of the starting materials or feed canrequire a cooling step to precipitate the resultant sodium and/orpotassium sulfate salts, such as Na₂SO₄.10H₂O, K₂SO₄, KLiSO₄.H₂O,NaLiSO₄.H₂O, and the like. The use of chloride salts as startingmaterials or feed can require higher temperatures to reject theresultant sodium salt NaCl and lower temperatures for the resultantpotassium salt KCl from aqueous metathesis salting out. To purify LiNO₃and/or LiBr salt solutions, a solvent step metathesis step can berequired for precipitation removal of sodium and/or potassium aschloride and/or sulfate salts.

In a specific embodiment of the invention, the process for preparing alithium salt of formula LiX having a desired or required puritycomprises dissolving lithium chloride, lithium sulfate, or a mixturethereof and a NaX salt, KX salt, or mixture thereof, in an aqueoussolution and filtering the solution to remove the precipitated sodiumand potassium salts. An aliphatic ketone, an aliphatic alcohol, or amixture thereof, is then added to the solution to form a semiaqueoussolution, and the precipitated sodium and potassium salts are againfiltered from the solution. In addition, a monovalent cation sulfatesalt can be added to the semiaqueous solution to cause the salting outor precipitation of undesired sodium and potassium salts from thesolution thereby purifying the solution. The organic solvent is thenremoved and the resulting LiX solution of desired purity is recovered.The LiX solution can then be dried where solid LiX salt is desired asthe end product or stored and sold in solution.

These and other features and advantages of the present invention willbecome more readily apparent to those skilled in the art uponconsideration of the following detailed description which describes boththe preferred and alternative embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The process of the invention comprises preparing a lithium salt offormula LiX having a desired or required purity by reacting a lithiumsalt selected from lithium chloride, lithium sulfate, and combinationsthereof with NaX or KX in an aqueous, semiaqueous or organic solutionand removing the precipitated solids from the solution to obtain a LiXsolution of desired purity. Any combination of solvents can be used inaccordance with the invention. Preferably, a semiaqueous solution isused containing water and an organic solvent. The reaction can also beinitiated in an aqueous solution and then continued in either asemiaqueous or an organic solution to provide the LiX salts of theinvention. As used herein, and as will be appreciated by the skilledartisan, the term “salt” unless otherwise specifically defined can referto a salt provided in solid or liquid form (for example as brinesolutions).

The lithium chloride and lithium sulfate salts used in the process areinexpensive and readily available in anhydrous form, hydrated form, orin solution. Typically, the lithium chloride is obtained in purifiedform as a liquid as well as an anhydrous salt from geothermal brinedeposits such as those in Chile and Argentina by selective adsorptionand solar evaporation. Lithium sulfate is obtained from spodumene ore byconventional roasting, acid leach and purification steps, and from brineby conventional routes. The NaX or KX salts are also available inanhydrous form, hydrated form, or in solution and can be available asmixtures of NaX and KX. Advantageously, the lithium chloride, lithiumsulfate, NaX and KX can be used in liquid and well as solid form. Thus,where the transport of the raw materials is not a concern, the lithiumchloride, lithium sulfate, NaX and KX can be used in liquid form andthus do not require drying. As a result, the cost of the raw materialsused in the process is reduced.

The process of the invention is preferably initiated by dissolvinglithium chloride, lithium sulfate, or a mixture thereof and a NaX salt,KX salt, or a mixture thereof, in an aqueous solution. The dissolutionof these reactants occurs by dissolving lithium chloride or lithiumsulfate in a NaX or KX solution, dissolving NaX or KX in a lithiumchloride or lithium sulfate solution, or mixing an aqueous solution oflithium chloride or lithium sulfate with an aqueous solution of NaX orKX. In addition, the solution can be heated and/or agitated tofacilitate the dissolution of the salts in the solution. Preferably, thedissolving step is conducted at between 0 and 120° C. and underatmospheric or subatmospheric pressure (5 to 25 mm Hg).

As the salts are combined in solution, the lithium chloride and lithiumsulfate reacts with the NaX and KX salts in a substitution or metathesisreaction to form LiX as the desired end product and NaCl, Na₂SO₄, KCl,K₂SO₄ and the like as by-products. The LiX is preferably more soluble inthe aqueous solution than the sodium and potassium salts, i.e. the saltby-products and any excess NaX or KX present in the solution, therebycausing the sodium and potassium salts to precipitate out of solutionbefore the LiX salt. The solution is often concentrated such as byevaporating off the water or other means to thereby increaseprecipitation of the sodium and potassium salts. Preferably, thesolution is concentrated such that the solution contains from greaterthan 0 to about 4 moles of water per mole of LiX. More preferably, theaqueous solution contains between about 1 mole and 3 moles of water permole of LiX. The amount of water in solution is preferably sufficient tokeep the LiX in solution below or close to saturation at the operatingtemperature. Typically, the pH of the aqueous solution is between about5 and 10, preferably between about 6 and 8. In addition, where thesolution has been heated, the solution can be cooled to help precipitatemore sodium and potassium salts from the solution. Once the sodium andpotassium salts precipitate, these salts can be removed from the aqueoussolution by continuously filtering the solution or other suitable means.

Once the partially precipitated sodium and potassium salts have beenremoved from the aqueous solution for further purification, an organicsolvent is added to the aqueous solution to form a semiaqueous solution.Alternatively, the water can be removed completely in the solution andthe organic solvent added to form an organic solution. Typically, thesolution is agitated and can be heated to facilitate the formation ofthe semiaqueous or organic solution. It can also be beneficial in thecase of the semiaqueous solution to dilute the solution by adding waterto the solution to bring the amount of dissolved solids in the solutionto less than 50 weight percent prior to adding the organic solvent. Thepreferred organic solvents for use in the process of the invention arealiphatic ketones (e.g. primary and secondary C1-C10 ketones), aliphaticalcohols (e.g. primary and secondary C1-C10 alcohols), and mixturesthereof. Exemplary ketones and alcohols include without limitationacetone, dimethylketone, diethylketone, methanol, ethanol, propanol,pentanol, hexanol, and the like, and preferably is acetone, methanoland/or ethanol, and more preferably acetone and/or methanol.

Preferably, the amount of organic solvent in the semiaqueous or organicsolution is greater than 0 moles and less than 10 moles per mole of LiX.More preferably, the amount of organic solvent is between about 0.25moles and about 3 moles per mole of LiX. The amount of water present inthe semiaqueous solution is as described above. Preferably, the amountof water (semiaqueous solution) and organic solvent in the semiaqueousor organic solution is sufficient to keep the LiX in solution below orclose to saturation at the operating temperature. The addition of theorganic solvent and filtration of the precipitated solids is typicallyconducted at between 0 and 60° C., preferably, between about 0° C. and30° C., and under atmospheric or subatmospheric pressure (0 to 25 mmHg). In addition, the pH of the semiaqueous solution is typicallybetween about 5 and 10, preferably between about 7 and 9.

Once the organic solvent has been added to the solution, additionalsodium and potassium salts precipitate out of the semiaqueous solution.In addition to the organic solvent, a sulfate salt having a monovalentcation, e.g., an alkali metal sulfate, such as but not limited toNa₂SO₄, Na₂SO₄.10H₂O, LiSO₄, LiSO₄.H₂O, KLiSO₄.1/2H₂O, K₂SO₄, andNaLiSO₄.H₂O, and the like, can be added to the solution with the organicsolvent or prior to drying the aqueous solution to facilitateprecipitation of the sodium and potassium salts. Preferably, the addedsulfate salt is sodium sulfate or potassium sulfate to correspond to thesalt originally added in the process to provide the X anion for the LiXsalt. The precipitated salts are removed from the semiaqueous solutionsuch as by filtering. In addition, where elevated temperatures are usedfor the semiaqueous solution, the solution temperature can be decreasedto cause greater precipitation of the sodium and potassium salts.

Once the precipitated solids have been substantially removed from thelithium solution, the organic solvent is removed next from the solution.The organic solvent can be recycled into the process. The recovery ofthe organic solvent from the solution is preferably facilitated byconcentrating the solution such as by heating the solution to evaporate(distillation) the organic solvent. The resulting LiX solution or saltcan have a purity of 95% or greater, preferably 99% or greater, and isrecovered in the process. When a semiaqueous solution is used, the LiXsolution can then be concentrated to increase the amount of solids inthe solution or dried to form a LiX salt of desired purity.

Although the process of the invention is described as a two-step processin which precipitation occurs first in an aqueous solution and then in asemiaqueous or organic solution, the process can be conducted as aone-step process wherein only the semiaqueous solution is used under thesemiaqueous conditions described above. In particular, the one-stepprocess is preferred wherein LiX is less soluble in water than thesodium and potassium salts but more soluble in the semiaqueous solutionthan the sodium and potassium salts. In addition, the process of theinvention can be conducted in a batch, semi-batch or continuous processto produce the LiX salts. Preferably, for the large-scale production oflithium salts, a continuous or semi-batch process is used in accordancewith the invention.

The present invention can be used to form various LiX salts. Preferably,as will be readily understood to one skilled in the art, the process ofthe invention is used to produce LiX salts having a greater solubilityin the solutions used than the sodium or potassium salts present inthese solutions. In particular, the process of the invention can be usedto produce a lithium salt of formula LiX wherein X is an anion selectedfrom nitrate, bromide, chloride, iodide, borate (tetraborate), acetate,pentaborate, acetylsalicylate, amide, benzoate, chlorate, perchlorate,chloroplatinate, chromate, citrate, dichromate, fluosilicate,fluosulfonate, formate, hydroxide, hypochlorite, iodate, lactate,permanganate, methoxide, molybdate, nitrite, niobate, oxalate, oxide,salicylate, sulfate, sulfide, sulfite, tartrate, thiocyanate,dithionate, tungstate, and vanadate. Preferably, the process of theinvention is used to make lithium nitrate or lithium bromide.

The process of the invention allows LiX to be produced from NaX and KXsalts which are generally more readily available and are therefore lessexpensive than the related LiX salts. For example, sodium nitrate (alsocalled Chilean nitrate or Chile saltpeter) is abundantly available inSouth American salt deserts and potassium nitrate is made from sodiumnitrate in Chile. Sodium bromide is recovered as a by-product fromsolutions obtained during bromination, bromo-oxidation and hydrolysis oforganic bromide compounds. Furthermore, large amounts of potassiumbromide are made from the neutralization of HBr with KOH or K₂CO₃. Anyexcess NaX and KX salts which are recovered in the process can beseparated and recycled into the process.

Another advantage of the process of the invention is that high purityraw materials are not required to produce the LiX solutions or saltshaving the desired or required purity. Specifically, because undesiredsalts generally precipitate out of the solution during the process ofthe invention, impurities can be present in the raw materials. Thus,more expensive high purity raw materials are not necessary in order toproduce LiX having a desired purity according to the invention.

A further advantage of the process is that the salt by-products, i.e.,the sodium and potassium salts, are useful chemicals and thus are notdiscarded as waste. For example, potassium chloride is a raw materialfor manufacturing potassium nitrate from Chile saltpeter (NaNO₃) andpotassium sulfate is a very valuable potash fertilizer. In addition,NaCl (table salt) and Na₂SO₄ (salt cake) have uses which are well knownin the art.

The present invention provides an inexpensive process for thepreparation of lithium salts using lithium chloride and lithium sulfate.The process of the invention eliminates the use of highly acidicmaterials and thus reduces the cost of raw materials and the need forspecialized equipment. Therefore, the process produces lithium saltshaving a desired or required level of purity without compromising safetyin the production of these salts. Additionally, lithium chloride andlithium sulfate can be used in both solid and solution form in theprocess and thus do not have to be dried out prior to use.Advantageously, the by-products of the process of the invention haveother useful applications and thus the process produces little waste.

The present invention will now be further illustrated by the followingnon-limiting examples. All percentages unless otherwise indicated are ona per weight basis.

EXAMPLE 1

Five hundred grams of water in a 1000 ml beaker was heated to 60° C. and210 g NaNO₃ was added with slow agitation to obtain a clear solution.Next, 100 g of anhydrous high purity LiCl was added slowly to the NaNO₃solution with agitation to again obtain a clear solution. Next, thebrine was allowed to concentrate by removing water and salt formationstarted after removal of about 150-200 g water. The evaporation of waterand the salt removal by filtration of the warm slurry was continueduntil the final filtrate reached 350 g. The salt cake was washed withfine water spray and the wash was recycled with the mother liquor. Next,the filtrate was allowed to cool to 20° C. and filtered to removesolids. The filtrate (about 295 g) and the total solids (about 142 g)was recovered and sampled for analysis. The analysis of the filtrateshowed 5.58% Li⁺, 1.66% Na⁺, 54.39% NO₃ ⁻ and 0.22% Cl⁻. Next, 200 ml ofthe filtrate was diluted with water to about 240 ml to bring the totaldissolved solids to below 50%. One hundred milliliters of dimethylketonewas added to the filtrate with slow agitation and at room temperature.The mixture was allowed to agitate for 60 minutes and then filtered toremove solids. The filtrate was concentrated to recover dimethylketoneat low pressure and a temperature between 25 and 60° C. The finalsolution once free from organic solvent was analyzed and contained 4.64%Li⁺, 0.105% Na⁺, 41.369% NO₃ ⁻, and less than 0.2% Cl⁻.

EXAMPLE 2

Four hundred twenty-five (425) grams of water in a 1000 ml beaker washeated to 65° C. and 450 g NaNO₃ was added to the beaker and dissolvedcompletely. Next, 215 g anhydrous LiCl was dissolved in 375 g of waterin a separate beaker. The LiCl solution was added slowly to the NaNO₃solution with agitation. The resulting solution turned into a slurryindicating precipitation of the NaCl salt. The solution was concentratedby removing about 200 g of water. The 1265 g slurry was filtered hot andthe filter cake was washed with 30 g of a water spray. The resulting wetcake was dried and weighed 123 g. The filtrate was concentrated furtherto 980 g by removing 195 g of water. The resulting slurry was filteredand the filter cake was washed with 20 g of water. The filter cake wasdried and weighed 32 g. Next, the 968 g filtrate and wash wereconcentrated in a similar fashion in two steps at 90° C. to obtain 620 gfiltrate and 90 g washed dry salts. A total of 45 g of water was used towash the filter cake in these two steps. The filtrate (620 g) andcollected salts were analyzed using conventional techniques andcontained the following:

Hot Filtrate Salts Li⁺ 5.60% 0.20% Na⁺ 4.65% 37.90% NO₃ ⁻ 52.22% 1.79%Cl⁻ 5.50% 58.42%

EXAMPLE 3

Twenty-three grams of Glauber salt (Na₂SO₄:10H₂O) was added to 310 g ofthe hot filtrate from Example 2 and the solution was allowed toconcentrate to dryness using rotovap. The dried salts were cooled to 50°C. Next, 250 ml of absolute methyl alcohol was added to the dried saltswith agitation. The slurry was agitated between at room temperature and50° C. to dissolve LiNO₃. After three hours of agitation at any giventemperature between 10° C. and 50° C., the slurry was filtered to removeundissolved salts. The filtrate and the solids were dried under vacuumto recover alcohol for recycling into the process and both of theresulting solids were analyzed. The results were as follows:

LiNO₃ solids from Undissolved alcohol filtrate Salts Wt. 170 g 55 g Li⁺9.900% 0.90% Na⁺ 0.380% 30.90% NO₃ ⁻ 87.260% 24.60% Cl⁻ 0.068% 30.90%SO₄ ²⁻ 0.005% 12.30%

EXAMPLE 4

Twenty-three grams of Glauber salt (Na₂SO₄:10H₂O) was added to 310 g ofthe hot filtrate from Example 2 with agitation. The solution was cooledto 50° C. and 250 ml of ethyl alcohol was added to the solution withagitation. The solution was allowed to cool down to 20° C. After threehours of agitation at 20° C., the slurry was filtered to remove salts.The alcohol was recovered from the process for recycling into theprocess and the solution and filtered solids were analyzed. The resultswere as follows:

LiNO₃ soln. from Undissolved alcohol filtrate Salts Wt. 350 g 47 g Li⁺4.850% 0.77% Na⁺ 0.472% 34.05% NO₃ ⁻ 44.145% 15.70% Cl⁻ 0.290% 34.15%SO₄ ²⁻ 0.009% 14.32%

EXAMPLE 5

Five hundred grams of water in a 1000 ml beaker was heated to 60° C. and250 g anhydrous NaBr was added to obtain a clear solution. Next 100 g ofanhydrous LiCl was added slowly with moderate agitation. The mix wasallowed to agitate for one hour at between 60°C. and 80° C. Fine whitesolids were precipitated from the metathesis reaction. Next, the slurrywas concentrated by removing water under low pressure and the slurry wasfiltered simultaneously to remove solids. The solid wet cake was washedwith fine water spray to recover LiBr entrainment. The filtrate and thewash were recycled to the evaporator. The evaporation and filtrationwith washing of the filter cake was continued until the final filtratewas about 320 g. The filtrate was allowed to cool to 20° C. and filteredagain to remove salts from the solution. The clear brine filtrate (about250 g) and the total solids (about 152 g) were sampled for analysis. Thechemical analysis of the brine solids showed 5.2% Li⁺, 0.153% Na⁺, 53%Br⁻, and 0.064% Cl⁻. The filtrate from evaporation and cooling can thenbe mixed with diketones, such as acetone, and/or a low carbon primaryalcohol, such as methanol, to precipitate out excess sodium halide saltsto obtain a final product solution of LiBr with very low sodium andchloride content.

It is understood that upon reading the above description of the presentinvention, one skilled in the art could make changes and variationstherefrom. These changes and variations are included in the spirit andscope of the following appended claims.

That which is claimed:
 1. A method for preparing a lithium salt offormula LiX, comprising: reacting lithium salt selected from lithiumchloride, lithium sulfate, and combinations thereof with NaX or KX in anaqueous solution; adding an organic solvent to the aqueous solution toproduce a semiaqueous solution; and removing the precipitated solidsfrom the semiaqueous solution to obtain a LiX solution.
 2. The method ofclaim 1 wherein said adding step comprises adding an organic solventselected from aliphatic ketones, aliphatic alcohols, and mixturesthereof.
 3. The method of claim 1 further comprising, prior to saidadding step, the step of solution removing the precipitated solids fromthe aqueous solution.
 4. The method of claim 1 wherein X of the NaX orKX salts in the reacting step is selected such that the solubility ofLiX in the aqueous solution is greater than the solubility of the sodiumor potassium salts produced in the reacting step and the solubility ofLiX in the semiaqueous solution is greater than the solubility of thesodium or potassium salts produced in the reacting step.
 5. The methodof claim 1 wherein X is an anion selected from nitrate, bromide,chloride, iodide, acetate, borate (tetraborate), pentaborate,acetylsalicylate, amide, benzoate, chlorate, perchlorate,chloroplatinate, chromate, citrate, dichromate, fluosilicate,fluosulfonate, formate, hydroxide, hypochlorite, iodate, lactate,permanganate, methoxide, molybdate, nitrite, niobate, oxalate, oxide,salicylate, sulfate, sulfide, sulfite, tartrate, thiocyanate,dithionate, tungstate, and vanadate.
 6. A method for preparing lithiumnitrate or lithium bromide, comprising: reacting lithium salt selectedfrom lithium chloride, lithium sulfate, and combinations thereof withNaNO₃, NaBr, KNO₃ or KBr in an aqueous, semiaqueous or organic solution;and removing the precipitated solids from the solution to obtain a LiNO₃or LiBr solution.
 7. The method of claim 1 further comprising the stepof adding a sulfate salt having a monovalent cation to the semiaqueoussolution.
 8. A method for preparing a lithium salt of formula LiX,comprising: reacting lithium salt selected from lithium chloride,lithium sulfate, and combinations thereof with NaX or KX salt in anaqueous solution; removing the precipitated solids from the aqueoussolution; drying the aqueous solution and recovering the dried salts;preparing an organic solution comprising the salts from said dryingstep; and removing the precipitated solids from the organic solution. 9.A method for preparing a high purity lithium salt of formula LiXcomprising: dissolving lithium chloride, lithium sulfate, or a mixturethereof and a NaX salt, KX salt, or a mixture thereof, in an aqueoussolution; filtering the solution to remove the sodium and potassiumsalts; adding an organic solvent selected from an aliphatic ketone, analiphatic alcohol and a mixture thereof, to form a semiaqueous solution;filtering the precipitated sodium and potassium salts from thesemiaqueous solution; removing the organic solvent from the solution;and recovering the resulting LiX solution.
 10. The method of claim 9further comprising the step, after said dissolving step, ofconcentrating the salts in the solution thereby increasing precipitationof the sodium and potassium salts.
 11. The method of claim 9 wherein thestep of removing the organic solvent from the solution comprisesconcentrating the solution to facilitate removal of the organic solventfrom the solution.
 12. The method of claim 9 wherein X is selected suchthat the solubility of LiX in the aqueous and semiaqueous solutions isgreater than the solubility of the sodium or potassium salts produced inthe reacting step.
 13. The method of claim 9 wherein X is an anionselected from nitrate, bromide, chloride, iodide, acetate, borate(tetraborate), pentaborate, acetylsalicylate, amide, benzoate, chlorate,perchlorate, chloroplatinate, chromate, citrate, dichromate,fluosilicate, fluosulfonate, formate, hydroxide, hypochlorite, iodate,lactate, permanganate, methoxide, molybdate, nitrite, niobate, oxalate,oxide, salicylate, sulfate, sulfide, sulfite, tartrate, thiocyanate,dithionate, tungstate, and vanadate.
 14. A method for preparing highpurity lithium nitrate or lithium bromide, comprising: dissolvinglithium chloride, lithium sulfate, or a mixture thereof and a NaX salt,KX salt, or a mixture thereof, wherein X is nitrate or bromide, in anaqueous solution; filtering the solution to remove the sodium andpotassium salts: adding an organic solvent selected from an aliphaticketone, an aliphatic alcohol and a mixture thereof, to form asemiaqueous solution; filtering the precipitated sodium and potassiumsalts from the semiaqueous solution; removing the organic solvent fromthe solution: and recovering the resulting lithium nitrate or lithiumbromide solution.
 15. The method of claim 9 further comprising the stepof drying the LiX solution to form a LiX salt having a desired level ofpurity.
 16. The method of claim 9 wherein said step of dissolvingcomprising heating thee solution and said method further comprises thestep of heating and cooling and filtering the solution to removeadditional sodium and potassium salts prior to said step of adding anorganic solvent.
 17. The method of claim 9 further comprising the stepof diluting the solution to bring the amount of dissolved solids in thesolution to less than 50 weight percent prior to the step of adding anorganic solvent.
 18. The method of claim 9 wherein after said step ofadding the organic solvent, the amount of water in the semiaqueoussolution is greater than 0 moles and less than 4 moles per mole of LiXand the amount of organic solvent in the solution is greater than 0moles and less than 10 moles per mole of LiX.
 19. The method of claim 9wherein the amount of water in solution during said first filtering stepis sufficient to keep the LiX in solution below or close to saturationat the operating temperature.
 20. The method of claim 9 wherein theamount of water and organic solvent in the solution during said secondfiltering step is sufficient to keep the LiX in solution below or closeto saturation at the operating temperature.
 21. The method of claim 9wherein the first filtering step is conducted at between 0 and 120° C.and under atmospheric or subatmospheric pressure.
 22. The method ofclaim 9 wherein the second filtering step is conducted at between 0 and60° C. under atmospheric or subatmospheric pressure.
 23. The method ofclaim 9 further comprising the step of adding a sulfate salt having amonovalent cation to the semiaqueous solution.
 24. The method of claim23, wherein said monovalent cation sulfate salt is selected from Na₂SO₄,Na₂SO₄.10H₂O, LiSO₄, LiSO₄.H₂O, KLiSO₄.1/2H₂O, K₂SO₄, and NaLiSO₄.H₂O.25. A method for preparing lithium nitrate or lithium bromide,comprising: reacting lithium salt selected from lithium chloride,lithium sulfate, and combinations thereof with NaX or KX, wherein X isnitrate or bromide, in an aqueous solution; adding an organic solvent tothe aqueous solution to produce a semiaqueous solution; and removing theprecipitated solids from the semiaqueous solution to obtain a LiXsolution.